1. Field of the Invention
This invention relates in general to a method and apparatus for floating drilling rig operations. In particular, the invention relates to a remotely operable system for connecting or disconnecting upper flexible choke and kill lines to the choke and kill lines associated with the drilling riser system. Still more particularly, the invention relates to a method of assembling a blowout preventer stack and marine riser system from the sea floor to the drilling rig and to the equipment for connecting flexible choke/kill lines to the choke/kill lines secured to the marine riser.
2. Description of the Prior Art
In floating drilling systems, a blowout preventer stack system is connected to the wellhead at the sea floor and is connected to the drilling rig by means of a riser system. The riser system is an assembly of end-to-end connected riser lengths or "joints", each of which is constructed of seamless pipe with mechanical connectors welded on their ends. Choke/kill lines are attached to the riser lengths by extended flanges of the connectors.
In general, the riser is run in a manner similar to drill pipe, that is, by stabbing one riser length at a time into the string and tightening the connector. The choke/kill lines attached to the pipe of the riser lengths are made up simultaneously with the pipe, until the entire riser string runs from the blowout preventer stack at the sea floor to a position at the vessel where the riser system is completed by connecting flexible drape hoses to the choke/kill line. A telescopic joint, flex joint/diverter system, is connected to complete the drilling riser system.
In conventional systems, the blowout preventer stack is first landed on the sea floor and the riser string is constructed by connecting the riser lengths end to end. The choke/kill lines running parallel to the riser lengths at this time in the assembly face upwardly in the moon pool of the drilling vessel and are unterminated. They must be connected to flexible drape hoses by means of stab connectors. Prior art systems for such connection have required manual maneuvering of the heavy, awkward drape hoses and equipment into place with the assistance of various tugger lines.
Prior systems for connecting the drape hoses to the choke/kill lines of the riser have used pinned connections with associated loose parts and tools which can be lost overboard into the sea. These systems have required manual connection and tugger lines, often with a workman held by a sling beneath the rotary table in the moon pool. With such a system, the workman must struggle with drape hose bundles often weighing as much as 3,000 lbs.
Still other systems have provided for semi-automatic connection of the drape hoses to the choke/kill lines. But such systems have not provided a way for moving the drape hoses out of the interfering vicinity beneath the rotary table of the vessel so that the blowout preventer stack may be moved in the moon pool beneath the rotary table for connection to the riser in anticipation of lowering the riser and the stack to the sea floor.